1. Field of the Invention
The present invention relates to a heat exchanger, and particularly to a composite heat exchanger having functions of air cooling and spray cooling thereby enhancing heat transfer efficiency.
2. Prior Art
As it is well known, air coolers are used to provide us comfortable living conditions thereby helping us to live through a hot summer. The diffusion rate of air coolers is about 85.9% of domestic users. Electricity consumption of air coolers occupies about 30% during electricity consumption peak of summer, which shows that air coolers consume a great amount of electric energy. For saving energy and increasing efficiency of electricity consumption, it is desired to increase energy efficiency ratio (EER) of air coolers. U.S. Pat. Nos. 5,946,932, 4,672,817, 6,598,862, and 6,766,655 and Taiwan Patent No. 367033 disclose different heat exchangers of air coolers for encountering the above problem.
As shown in FIGS. 1–2, a conventional heat exchanger having a plurality of fins is designed to exchange heat with air as the heat exchange medium and so has a function of air cooling. The heat transfer rate of the heat exchanger depends on area of the fins 5 and air flow velocity. However, by using the air cooling type heat exchanger as condenser of the air cooler causes water to drop from it, which is inconvenient to use.